1. Field of the Invention
The present disclosure relates to identification of quantitative trait loci (QTLs) and gene(s) that confer upon a soybean plant resistance to soybean cyst nematode (SCN) and methods to use these loci and genes to obtain soybean strains that are resistant to SCN.
2. Description of the Related Art
Soybean cyst nematode (SCN), Heterodera glycines, is one of the most destructive pests of soybean in the United States and worldwide. Although nematocides may be used to reduce the population of nematodes, the use of nematocides is neither economical nor environmentally friendly. Host plant resistance is an effective approach to control this pest; however, continuously growing the same resistant cultivar(s) may result in SCN population shifts and loss of SCN resistant phenotype.
Since the discovery of SCN in the United States in the 1970s, extensive efforts have been made to identify new SCN resistance sources by screening Glycine max plant introductions (PIs) of the USDA soybean germplasm collection (Anand et al. 1988; Arelli et al. 2000; Arelli et al. 1997; Young 1995). Chen et al. (2006) used bioassay to characterize over 120 SCN resistance soybean accessions with SCN races 3, −5, and −14 and reported many PIs including PI 437654, PI 438489B, PI 90763, PI 89772, PI 404198A, and PI 567516C with high resistance levels to multi-races.
Although several SCN resistance quantitative trait loci (QTLs) have been discovered in PI 437654 (Concibido et al., 2004, U.S. Pat. No. 6,096,944 issued to Vierling et al. and U.S. Pat. No. 6,538,175 issued to Webb), many SCN resistance QTLs remain to be identified. More SCN sources of resistance have been evaluated extensively to identify novel QTLs and epistatic effects between QTLs (Wu et al 2009). Among soybean PIs evaluated for SCN resistance, PI 437654, PI 467312, PI 438489B, and PI 567516C have been reported to be highly resistant to multi-races (also known as HG types) of SCN. In addition, PI 567516C is also resistant to a synthetic nematode population LY1 and genetically unique from most other SCN resistant sources, including Peking and PI 88788 that are widely used in current SCN resistant varieties.